A Wi-Fi (Wireless Fidelity) technology is a short-distance wireless communications technology, and is already widely used due to its advantages such as a free spectrum and a high transmission rate. For example, in a scenario in which an AP (Access Point, access point) is disposed at an airport, or in a restaurant or a conference room, a Wi-Fi device accesses a network by using the AP. For another example, in a scenario in which no AP is disposed, Wi-Fi devices directly communicate with each other to implement data sharing between the Wi-Fi devices and use of various services, that is, communication is implemented between the Wi-Fi devices.
For the scenario in which no AP is disposed, the Wi-Fi Alliance (Wi-Fi Alliance) puts forward a NAN (Neighbor Awareness Network, neighbor awareness network) technology to implement synchronization and service discovery between the Wi-Fi devices and then achieve an objective of implementing communication between the Wi-Fi devices.
FIG. 1 is a schematic diagram of a DW (Discovery Window) of a neighbor awareness network device cluster on a sixth channel of 2.4 GHz frequency band. As can be seen from FIG. 1, in a same neighbor awareness network device cluster, time duration of a DW is fixed, and a time interval between any two neighboring DWs is fixed. In a DW, both a Master (master device) and a Non-Master Sync (non-master synchronization device) that are in the neighbor awareness network device cluster may contend for sending a Sync Beacon (synchronization beacon frame) to implement device synchronization in a network; however, at other time beyond the DW, the Master sends a Discovery Beacon (discovery beacon frame) to announce existence of the neighbor awareness network device cluster.
As can be known from the description of the neighbor awareness network technology, multiple Wi-Fi devices may join a neighbor awareness network device cluster, and implement synchronization between the Wi-Fi devices and service search and discovery in a DW of the neighbor awareness network device cluster. Because the time duration of a DW is shorter than the time interval between two neighboring DWs, and a Wi-Fi device needs to, only within the very short time duration of the DW, listen on a working channel and perform service discovery, the Wi-Fi device may perform service search and discovery continuously in a low power consumption mode.
When a Wi-Fi device scans a working channel of a neighbor awareness network and discovers multiple neighbor awareness network device clusters, the Wi-Fi device may join each neighbor awareness network device cluster, and implement synchronization and service search and discovery in each neighbor awareness network device cluster. That is, the Wi-Fi device needs to perform channel listening in a DW of each neighbor awareness network device cluster, participate in an election of a synchronization device, and be synchronized to the discovery window of the neighbor awareness network device cluster to perform service discovery, thereby implementing service search and discovery.
Assuming that the Wi-Fi device joins two neighbor awareness network device clusters (which may be separately called neighbor awareness network device cluster-A and neighbor awareness network device cluster-B), FIG. 2 shows a schematic diagram of composition of a neighbor awareness network in which the Wi-Fi device joins the neighbor awareness network device cluster-A and the neighbor awareness network device cluster-B, and FIG. 3 shows a schematic diagram of the neighbor awareness network device cluster-A and the neighbor awareness network device cluster-B that have a same working channel but unaligned DWs. The Wi-Fi device not only needs to, in an DW of the neighbor awareness network device cluster-A, listen on a channel, participate in an election of a synchronization device, and be synchronized to the discovery window of the neighbor awareness network device cluster to perform service discovery, but also needs to, in an DW of the neighbor awareness network device cluster-B, listen on a channel, participate in an election of a synchronization device, and be synchronized to the discovery window of the neighbor awareness network device cluster to perform service discovery. In a case in which service discovery needs to be performed continuously (possibly because no desired service is discovered for a long time or it is necessary to participate all the time in implementing service provisioning to the outside), the actual working time spent by the Wi-Fi device in joining multiple neighbor awareness network device clusters to perform service search and discovery is apparently longer compared with when the Wi-Fi device needs to join only one neighbor awareness network device cluster, and therefore, a relative power consumption of the Wi-Fi device is relatively high. In addition, on the working channel of the neighbor awareness network, DW resources of both the neighbor awareness network device cluster-A and the neighbor awareness network device cluster-B are occupied, and remaining available resources on the working channel are reduced, resulting in a problem of a relatively high resource usage of the working channel.
In conclusion, when the Wi-Fi device detects multiple neighbor awareness network device clusters and separately joins each neighbor awareness network, actual working time spent by the Wi-Fi device in service search and discovery is prolonged, power consumption of the Wi-Fi device is increased, and available resources on the working channel are reduced. Therefore, currently it is urgent to find a solution that can maintain a low power consumption of the Wi-Fi device without excessively occupying available resources of the working channel of the neighbor awareness network in a case in which the Wi-Fi device detects multiple neighbor awareness network device clusters.